Having played my first ever game of 30k, the following are my initial thoughts:
It's fun! The rules are complex without being so byzantine as to feel clunky, they really lean into supporting a more cinematic experience over a streamlined tournament style game. We didn't get into challenges, and we beefed volley shots on charges by... forgetting... to do... them... and I'm sure we made other mistakes, but the game was still very fun.
Light vehicles are tankier than you'd think! Rhinos having 5 hull points and AV 12 up front, and my Araknae cannons having AV 12 all around with a 5++ invulnerable save and 5 hull points, and the kharybdis drop pod also having AC 12 all around and 5 hull points, kept them in the game longer than expected given the weight of fire getting thrown around.
Araknae quad cannons dish out a RIDICULOUS amount of credible mid-strength fire. I mostly shot it at terminators and the kharybdis drop pod (and did manage to pop the drop pod full of tartaros terminators, all of whom unfortunately made their emergency disembark without difficulty and then weathered the explosion unharmed) which is not it's ideal target, but he didn't bring any rhinos or tactical marines so I made the best of things, and they did pretty well despite trying to punch above their weight.
Line 2 is very strong, allowing my single surviving tactical sergeant to out-score the 2 terminators he was fighting on an objective.
Objectives in general are kinda the be-all and end-all of the standard missions. I'd be intrigued to see variant missions for all points levels, but if you're playing a standard mission, ignoring the objectives and going after your weaker opponent does not work out well for you. As my opponent found out, losing the game with 3 points to my 12 despite my own units getting pretty badly mauled and not making too much of an accounting in return.
Neither my Moritat (he got sliced to ribbons by tartaros terminators with lightning claws piling out of a kharybdis drop pod, RIP) nor my Praetor (she just never got attacked, hanging out with a tactical squad on an objective the whole game) did much all game, so I still look forward to seeing what the Moritat can do in the shooting phase and a Praetor with a paragon blade can do in the fight phase.
Tactical squads with bolters are actually really strong in the shooting phase, especially if they hold still, because bolters have Heavy (FP) which means they get 3 shots each at 24". They're s4 ap4 so they're not going to do a whole helluva lot against *terminators*, but against enemy tacticals or despoilers or the like, they'll account well for themselves I believe.
Chain bayonets may or may not be worthwhile if you're fighting other tactical squads, but they are about as effective as harsh language against tartaros terminators, as you might expect.
I actually remembered to use my reaction to shoot the kharybdis when it came in, which put some damage on it and allowed me to shoot it down two turns later. In the future hopefully I will be better about remembering to use my reaction for overwatch or whatever it's called; might have taken out a terminator or two as they charged my Moritat if I had. Oh, well.
Anyhow, final verdict: Fun! Much more my style than modern 40k, which is more focused on tournament-style competitive play. It's good to have both! People who like to chase tournaments and build competitive lists need a home, and so do people like me who prefer to build lore-friendly thematic lists. I'm glad to have 30k, and I'm glad 40k is keeping the tournament crowd entertained and not playing games against me. Very much looking forward to my next game- hopefully at 1500 points or even 3000 next time! Would love to see what my Saturnine Praetor and his Tartaros Command Squad can do in melee. It's gonna be gross hahaha.